1. Field of the Invention
Apparatuses consistent with the present invention generally relate to a semiconductor for macro and micro frequency tuning and an antenna and a frequency tuning circuit having the semiconductor. More particularly, the present invention relates to a semiconductor which incorporates a positive, intrinsic, negative (PIN) diode and Varactor diode into one element, and thus is capable of preventing drawbacks such as insertion loss, complexity of a direct current (DC) power supply circuit, size increase, or deterioration of linearity of the Varactor diode, and an antenna and a frequency tuning circuit having the semiconductor.
2. Description of the Related Art
The advancement of wireless communication technology has introduced a variety of wireless communication services for use on devices, such as mobile phones, Personal Digital Assistants (PDA), personal computers, or laptop computers. Such wireless communication services include Global System for Mobile (GSM) communication, Personal Communication Services (PCS), World Interoperability for Microwave Access (WiMAX), Wireless Local Area Network (WLAN), Wireless Broadband Internet (WiBro), and Bluetooth.
The GSM uses a band of 890 KHz˜960 MHz. PCS uses a band of 1.8 GHz. WiMAX uses a band of 3.6 GHz˜3.8 GHz band. WLAN uses a band of 2.4 GHz under IEEE 802.11b, which is the Industrial, Scientific & Medical band, and uses a band of 5 GHz under IEEE 802.11a, which is the Unlicensed National Information Infrastructure band.
In order to use different wireless communication services being provided at different frequency bands, a wireless terminal is typically equipped with a reconfigurable antenna capable of frequency tuning to a corresponding service band for the transmission and reception of wireless signal and frequency tuning for the channel shift in the service band, a tunable filter, and a matching circuit. The macro tuning generally refers to the frequency tuning from one service band to another, and the micro tuning refers to the frequency tuning in the same service band.
In order to construct a macro-tunable and micro-tunable antenna, filter, and matching circuit, a PIN diode and a Varactor diode can be used.
The resistivity of the PIN diode is dependent on the DC current applied to the diode. Essentially, the PIN diode allows an electric current to flow when the voltage applied to the PIN diode is over threshold voltage, and blocks the electric current when 0 V is applied to the PIN diode. While the PIN diode is connected to a radiator, a filter line, and a matching circuit of the antenna, the length of the radiator, filter line, and matching circuit can be shortened by turning off the PIN diode because it subsequently causes some parts of the radiator, filter line, and matching circuit to be shorted. Therefore, macro tuning is possible by the length adjustment of the antenna, filter, and matching circuit.
When the Varactor diode is employed, inter-channel change in the service band is possible by minutely shifting the frequency and according to the amount of backward voltage being fed.
However, insertion loss occurs if both the PIN diode and the Varactor diode are employed for the macro and the micro tuning, due to respective packaging of the elements. Furthermore, the Varactor diode, as it uses a depletion region rather than an I-region, does not provide good linearity. Furthermore, because inductors for RF block are required to be installed in each of the PIN diode and the Varactor diode to prevent the ingress of RF signal of the DC power supply circuit into the diodes, the DC power supply circuit has a complicated structure and increased size.